Heat pipe and method for manufactureing the same

ABSTRACT

An exemplary heat pipe includes a first pipe and a second pipe. The first pipe includes a condenser section and an evaporator section extending from the condenser section along a longitudinal direction thereof. The second pipe encloses the condenser section of the first pipe. The evaporator section is located at an outside of the second pipe. The second pipe includes a casing enclosing the condenser section, second wick structures and working fluid contained in the second wick structures. Opposite ends of each second wick structure are respectively adhered to an inner wall of the casing and an outer periphery of the condenser section.

BACKGROUND

1. Technical Field

The disclosure generally relates to a heat transfer apparatus, and more particularly to a heat pipe for removing heat from heat generating components.

2. Description of Related Art

As electronic products continue to develop, heat generated from electronic components of the electronic products become more and more. If the heat can not be removed rapidly, the electronic components are prone to be overheated.

What is needed, therefore, is an improved heat pipe which overcomes the above described shortcomings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal, cross-sectional view of a heat pipe according to an embodiment of the present disclosure.

FIG. 2 is an isometric view of a second pipe of the heat pipe of FIG. 1.

FIG. 3 is a transverse, cross-sectional view of the second pipe of FIG. 2.

FIG. 4 is a transverse, cross-sectional view of a mandrel used in a method for manufacturing a heat pipe according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments of heat pipes will now be described in detail below and with reference to the drawings.

Referring to FIG. 1, a heat pipe 100 in accordance with an embodiment of the disclosure is shown. The heat pipe 100 includes a first pipe 10 and a second pipe 20 enclosing an end of the first pipe 10.

The first pipe 10 includes a casing 13, a continuous first wick structure 12 attached to an inner wall of the casing 13, and working fluid contained in the casing 13.

The casing 13 is a metallic, hollow, elongated tube having an annular transverse cross section and a uniform thickness along a longitudinal direction thereof. Opposite ends of the casing 13 are sealed. The first wick structure 12 is evenly distributed around the inner wall of the casing 13 and extends along the longitudinal direction thereof. The first wick structure 12 is tube-shaped in profile, and usually selected from a porous structure such as grooves, sintered powder, screen mesh, or bundles of fiber, which enables it to provide a capillary force to drive condensed working fluid to flow back. An inner periphery of the first wick structure 12 defines a chamber 11 therein to allow vaporized working fluid flowing therethrough.

The first pipe 10 includes an evaporator section 15 disposed at an end thereof and a condenser section 17 disposed at the other end thereof along the longitudinal direction thereof. A length of the condenser section 17 along the longitudinal direction of the casing 13 is larger than that of the evaporator section 15.

Referring to FIGS. 2-3, the second pipe 20 is elongated and encloses the condenser 17 of the first pipe 10 therein. The second pipe 20 includes a casing 22, a plurality of second wick structure 21 attached to an inner wall of the casing 22, and working fluid contained in the casing 22.

The casing 22 is a metallic, hollow tube having an annular transverse cross section and a uniform thickness along a longitudinal direction thereof. One end of the casing 22 is closed and the other end of the casing 22 along the longitudinal direction of the casing 22 is open.

The second wick structures 21 are spaced from each other and evenly distributed around the inner wall of the casing 22. In this embodiment, the second wick structures 21 are made of sintered powder, such as copper powder or other suitable material. Each second wick structure 21 is an elongated strip and extends from the open end to the closed end of the casing 22 along a longitudinal direction of the casing 22. A transverse cross section of each second wick structure 21 is trapezoidal. Each second wick structure 21 has a convex outer end attached to the inner wall of the casing 22, and a concave inner end opposite to the outer end and attached to an outer wall of the condenser section 17 of the casing 13 of the first pipe 10. A width of each second wick structure 21 decreases from the outer end to the inner end. An elongated channel 23 is defined between each two adjacent second wick structures 21 to allow vaporized working fluid flow therethrough. In this embodiment, each elongated channel 23 is defined among the inner wall of the casing 22, the outer wall of the casing 13 of the first pipe 10, and side surfaces of two adjacent second wick structures 21. The inner ends of the second wick structures 21 define a receiving chamber 24 therebetween to receive the condenser section 17 of the first pipe 10 therein. A bore diameter of the receiving chamber 24 is equal to a diameter of the condenser section 17 of the first pipe 10.

The condenser section 17 of the first pipe 10 is received in the receiving chamber 24 and an outer periphery thereof intimately contacts the inner ends of the second wick structures 21. An edge of the opened end is shrunken and sealed to an outer wall of the evaporator section 15 of the first pipe 10. In this state, the condenser section 17 and the second pipe 20 cooperatively form a condensing portion of the heat pipe 100, and the evaporator section 15 of the first pipe 10 acts as an evaporating portion of the heat pipe 100.

When the heat pipe 100 is used, heat generated from heat generating components is absorbed by the evaporator section 15 and then transfers to the condenser 17 and the second pipe 20 to dissipate. According to a formulation Q=CMΔT (Q shows an average of heat transfer rates, C shows a specific heat, ΔT shows an varied temperature , and M shows a mass), when the mass is increased, the average of heat transfer rates of the heat pipe 100 is increased. In this disclosure, the condensing portion of the heat pipe 100 is formed by the condenser section 17 and the second pipe 20, so the mass of the heat pipe 100 is larger than a conventional heat pipe formed by a single tube such as first pipe 15, and so the average of heat transfer rates of the heat pipe 100 is improved.

The heat pipe 100 is manufactured by following steps:

Providing the first pipe 10 and the casing 22.

Providing a mandrel 30 and inserting the mandrel 30 in the casing 22 from the opened end. Referring to FIG. 4, the mandrel 30 includes a cylindrical main body 31 and a plurality of extending portions 33 radially extending from an outer periphery of the main body 31 and evenly spaced from each other. Each extending portion 33 is an elongated strip and extends along a longitudinal direction of the main body 31. A receiving space 35 is defined between each two adjacent extending portions 33. Outer ends of the extending portions 33 abut the inner wall of the casing 22.

Providing a plurality of metal powder and filling the metal powder in the receiving spaces 35 and sintering the metal powder to make the metal powder form a plurality of second wick structures 21.

Taking off the mandrel 30 to make the portions of the extending portions 33 located define the channels 23, and the main body 31 located define the receiving chamber 24.

Inserting the condenser section 17 of the first pipe 10 in the receiving chamber 24 of the second pipe 20 and shrinking the opened end of the casing 22.

Vacuuming and placing the predetermined quantity of the working fluid into the casing 22.

Sealing the opened end of the casing 22 to obtain the heat pipe 100.

It is to be further understood that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

What is claimed is:
 1. A heat pipe comprising: a first pipe comprising a condenser section and an evaporator section extending from the condenser section along a longitudinal direction thereof; and a second pipe enclosing the condenser section of the first pipe, the evaporator section located at an outside of the second pipe, and the second pipe comprising a casing enclosing the condenser section, a plurality of second wick structures and working fluid contained in the casing.
 2. The heat pipe of claim 1, wherein opposite ends of each second wick structure attached to an inner wall of the casing and an outer wall of the condenser section.
 3. The heat pipe of claim 2, wherein the second wick structures are spaced from each other and a channel is defined between each two adjacent second wick structures to allow vaporized working fluid flowing therethrough.
 4. The heat pipe of claim 3, wherein the second wick structures are evenly distributed around the inner wall of the casing of the second pipe.
 5. The heat pipe of claim 3, wherein each second wick structure has a convex outer end attached to the inner wall of the casing, and a concave inner end opposite to the outer end and attached to the outer wall of the condenser section, and a width of each second wick structure decreases from the outer end to the inner end.
 6. The heat pipe of claim 1, wherein the second wick structures are made of sintered powder.
 7. The heat pipe of claim 1, wherein the first pipe comprises a casing, a first wick structure attached to an inner wall of the casing and working fluid contained in the casing.
 8. The heat pipe of claim 7, wherein the first wick structure selected from a porous structure such as grooves, sintered powder, screen mesh, or bundles of fiber.
 9. The heat pipe of claim 7, wherein an inner periphery of the first wick structure defines a chamber therein to allow vaporized working fluid flowing therethrough.
 10. The heat pipe of claim 7, wherein a length of the condenser section along a longitudinal direction of the casing of the first pipe is larger than that of the evaporator section.
 11. A method for manufacturing a heat pipe comprising following steps: providing a first pipe, the first pipe comprising a condenser section and an evaporator section extending from the condenser section along a longitudinal direction thereof; providing a casing, the casing comprising a closed end and an open end opposite to the closed end along a longitudinal thereof; providing a mandrel and inserting the mandrel in the casing from the open end to the closed end, the mandrel comprising a main body and a plurality of extending portions extending outwardly from an outer periphery of the main body and spaced from each other, the extending portions abutting an inner wall of the casing; providing a plurality of metal powder and filling the metal powder in gaps between each two adjacent extending portions and sintering the metal powder to make the metal powder form a plurality of second wick structures; tacking off the mandrel and inserting the condenser section of the first pipe in the casing and the second wick structures abutting an outer wall of the condenser section; vacuuming and placing predetermined quantity of working fluid into the casing; and sealing the open end of the casing.
 12. The method of claim 11, wherein the extending portions radially extend from the outer periphery of the maim body and evenly spaced from each other.
 13. The method of claim 11, wherein the main body is cylindrical.
 14. The method of claim 11, wherein each extending portion is an elongated strip and extends along a longitudinal direction of the main body.
 15. The method of claim 11, wherein the casing of the second heat pipe is a metallic, hollow tube having an annular transverse cross section and a uniform thickness along a longitudinal direction thereof.
 16. The method of claim 11, wherein the first pipe comprises a casing, a continuous first wick structure adhered to an inner wall of the casing and working fluid contained in the first wick structure.
 17. The method of claim 16, wherein the casing of the first pipe is a metallic, hollow, elongated tube having an annular transverse cross section and a uniform thickness along a longitudinal direction thereof.
 18. The method of claim 11, wherein a length of the condenser section along a longitudinal direction of the casing of the first pipe is larger than that of the evaporator section.
 19. A heat pipe comprising: a first pipe comprising a casing, and a first wick structure and working fluid received in the casing; and a second pipe comprising a casing, and a second wick structures and working fluid received in the casing; wherein the casing of the first heat pipe comprises one end of inserted into the casing of the second pipe, and another end adapted to thermally connect a heat generating component. 